some improvements from Nick's review.

Author: DiannaHohensee

server/src/main/java/org/elasticsearch/common/util/concurrent/TaskExecutionTimeTrackingEsThreadPoolExecutor.java

@@ -264,10 +264,10 @@ public boolean trackingMaxQueueLatency() {
      * Uses the difference of {@link #totalExecutionTime} since the last polling request to determine how much activity has occurred.
      */
     private class UtilizationTracker {
-        volatile long lastPollTime = System.nanoTime();
-        volatile long lastTotalExecutionTime = 0;
+        long lastPollTime = System.nanoTime();
+        long lastTotalExecutionTime = 0;
 
-        public double pollUtilization() {
+        public synchronized double pollUtilization() {
             final long currentTotalExecutionTimeNanos = totalExecutionTime.sum();
             final long currentPollTimeNanos = System.nanoTime();
 

server/src/test/java/org/elasticsearch/threadpool/ThreadPoolTests.java

@@ -682,8 +682,9 @@ <T> T assertLatestMetricValueMatches(
             List<Measurement> measurements = meterRegistry.getRecorder()
                 .getMeasurements(instrumentType, ThreadPool.THREAD_POOL_METRIC_PREFIX + threadPoolName + name);
             assertFalse(name + " has no measurements", measurements.isEmpty());
-            assertThat(valueExtractor.apply(measurements.getLast()), matcher);
-            return valueExtractor.apply(measurements.getLast());
+            var latestMetric = valueExtractor.apply(measurements.getLast());
+            assertThat(latestMetric, matcher);
+            return latestMetric;
         }
     }